(1) Field of the Invention
The present invention relates to a head device which is levitated from a storage medium by an air flow between the storage medium and the head device when accessing the storage medium.
Recently, the use of a large-capacity storage medium, such as a magnetic disk, has grown, and there is an increasing demand for a disk drive capable of speedily accessing the storage medium at a high recording density. For use in such a disk drive, a head device which is levitated from the storage medium by an air flow between the storage medium and the head device when accessing the storage medium is known.
(2) Description of the Related Art
In a magnetic disk drive, a magnetic disk is rotated at a high speed, and a read/write head accesses the disk to read information from or write information to the disk. A head device which is levitated from the disk by an air flow between the disk surface and an air bearing surface of the head device when accessing the disk, is used in the disk drive.
FIG. 7 is a perspective view of an existing head device 101 of the above type. FIG. 8 is a side view of the head device 101. The dimensions of the head device 101 shown in FIG. 7 and FIG. 8 are enlarged for the sake of simplicity of description.
As shown in FIG. 8, the head device 101 and another head device 201, which confront each other, are provided in an existing disk drive (not shown). The head device 201 has a configuration that is essentially the same as a configuration of the head device 101. Actually, the head device 101 and the head device 201 are vertically spaced apart from each other at a very small distance. However, the dimension of the distance between the two heads shown in FIG. 8 is enlarged for the sake of simplicity of illustration. The head device 101 constitutes a lower head of the disk drive, and the head device 201 constitutes an upper head of the disk drive. A magnetic disk 104 is placed between the lower head 101 and the upper head 201.
When the disk 104 is rotated in the direction "X" indicated in FIG. 8, the head device 101 is, as shown in FIG. 8, separated or levitated from the bottom surface of the disk 104 by an air flow between the rotating disk 104 and the head device 101. A distance of the head device 101 from the disk 104 is very small. The head device 101 extends in a radial direction of the disk 104 and is placed at an intermediate location of the disk 104. The side of the head device 101 when viewed in a direction parallel to the radial direction of the disk 104 passing the center of the disk 104 is illustrated in FIG. 8. In this condition, the head device 101 accesses the disk 104 to read information from or write information to the disk 104.
The head device 101 is configured to be used with two types of magnetic disk, and includes a low-speed head 110 and a high-speed head 120. Both the heads 110 and 120 are formed integrally with the head device 101.
As shown in FIG. 7, the head device 101 generally has a head portion 103 and a slider 106. The head portion 103 functions to read information from or write information to the disk 104. The slider 106 supports the head portion 103 thereon. The slider 106 is placed out of contact with the disk 104, and configured such that the slider 106 can maintain the head device 101, levitated from the disk 104 by the air flow, at a certain height. As shown in FIG. 8, the slider 106 is supported by a gimbal 102 of a thin plate material.
In the head device 101 of FIG. 7, the head portion 103 includes the low-speed head 110 and the high-speed head 120. Both the heads 110 and 120 are made of a magnetic material and formed as an air bearing surface of the slider 106. The low-speed head 110 and the high-speed head 120 are provided on the disk-side surface of the slider 106 along the side edges of the slider 106, and both extend in the disk rotation direction "X" of the disk 104 in parallel to each other. A central groove 108 extending in the disk rotation direction "X" is provided between the head 110 and the head 120. The head 110 has a core 111 and a gap 112, both formed thereon, and the gap 112 is formed in the middle of the core 111. The head 120 has a core 121 and a gap 122, both formed thereon, and the gap 122 is formed in the middle of the core 121.
In the disk drive, the disk 104 is rotated at a rotation speed that matches the type of the disk 104 loaded therein, and one of the low-speed head 110 and the high-speed head 120 of the head device 101 is selected in accordance with the type of the disk 104. The head device 101 magnetically reads information from or writes information to the disk 104 by using a magnetic field in the vicinity of the gap (either the gap 112 or the gap 122) of the selected head.
The slider 106 has a front edge 106a on an air-inlet side of the slider 106, and a rear edge 106b on an air-outlet side of the slider 106. A slanted surface 105 is provided along the front edge 106a of the slider 106. The slanted surface 105 is at a given angle ".alpha." to a horizontal direction parallel to the disk rotation direction "X". The slanted surface 105 functions as an air flow guide surface which smoothly introduces an air flow from the disk 104 when rotated at a high speed.
Suppose that the disk 104 is rotated at a high speed and a flow of air is produced between the rotating disk 104 and the air bearing surfaces of the head device 101. The air passes through the central groove 108 between the head 110 and the head 120, and flows, at the same time, along the head portion 103 (both the head 110 and the head 120) in the disk rotation direction "X" from the front edge 106a to the rear edge 106b. Hence, the head device 101 is levitated from the disk 104 by the air flow between the disk 104 and the head device 101.
The head device 201 has the configuration that is essentially the same as the configuration of the head device 101 described above. Hence, when the disk 104 is rotated at a high speed, the head device 201 is levitated from the disk 104 by an air flow between the disk 104 and the head device 201 in the same manner.
FIG. 9 is a diagram for explaining a turbulent air flow produced at the rear end of the head device 101.
The air flowing from the rear end of the head device 101 is very likely to separate from the disk 104 because a reduced-pressure region 131 is created at the rear end of the head device 101. The air separating from the disk 104 is drawn to the reduced-pressure region 131, and a turbulent air flow 130 with vortices is produced as shown in FIG. 9.
In the above-described head device 101, the air flow is produced between the disk 104 and the head device 101 when the disk 104 is rotated at a high speed. The air flow passes through the head device 101 in the disk rotation direction "X" from the front edge 106a to the rear edge 106b. The reduced-pressure region 131 is created at the rear end of the head device 101. As described above, the air flow from the rear end of the head device 101 is very likely to separate from the disk 104, and the air separating from the disk 104 is drawn to the reduced-pressure region 131. The turbulent air flow 130 is produced at the rear end of the head device 101.
If the influence of the turbulent air flow 130 is significantly large, the rotating disk 104 and the head device 101 are subjected to vibrations by the turbulent air flow 130. If the disk 104 and the head device 101 are vibrated in the directions "Z1" and "Z2" indicated in the FIG. 9, by the turbulent air flow 130, the distance between the disk 104 and the gap 112 (or the gap 122) fluctuates when the head device 101 accesses the disk 104. Hence, in such a condition, the read/write operation of the head device 101 for the disk 104 becomes unstable and inaccurate. Further, the head device 101 may touch the disk 104 during the read/write operation because of the vibrations caused by the turbulent air flow 130. Hence, the disk 104 and the head device 101 are susceptible to damage during the read/write operation.